diff --git a/.travis.yml b/.travis.yml
index 1cdf54a..d14eb46 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -9,8 +9,9 @@ os:
 rvm:
   - "2.0.0"
   - "2.1" # latest 2.1.x
-  - "2.2.5" # TODO: switch to "2.2" once it works for OS X
-  - "2.3.1" # TODO: switch to "2.3" once travis fixes it
+  - "2.2.5"
+  - "2.3.3"
+  - "2.4.0"
   - "ruby-head"
   - "jruby-9.0.5.0"
   - "jruby-9.1.5.0"